Phototherapy bandage

ABSTRACT

A phototherapy bandage capable of providing radiation to a localized area of a patient for accelerating would healing and pain relief, photodynamic therapy, and for aesthetic applications. The phototherapy bandage may include a flexible light source that is continuous across the bandage for providing a selected light, such as a visible light, a near-infrared light, or other light, having substantially similar intensity across the bandage. The bandage may also be flexible and capable of being attached to a patient without interfering with the patient&#39;s daily routine. The phototherapy bandage may easily conform to the curves of a patient and may come in a variety of exterior shapes and sizes.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. application Ser. No.10/732,086, filed Dec. 10, 2003, which is a continuation-in-part of U.S.application Ser. No. 10/170,942, filed Jun. 12, 2002, and which claimsthe priority benefit of U.S. Provisional Application No. 60/432,284,filed Dec. 10, 2002.

FIELD OF THE INVENTION

The invention is directed generally to phototherapy, and moreparticularly, to methods and devices for administering radiation to atargeted site on a patient.

BACKGROUND

Phototherapy is the therapeutic use of light that has been recognized asan effective method of treating wounds and reducing pain in humans.External phototherapy has been effective in treating various medicalconditions, such as, but not limited to, bulimia nervosa, herpes,psoriasis, seasonal affective disorder, sleep disorders, acne, skincancer, hyperbilirubinemia in infants, and other conditions.Phototherapy is typically administered to a patient using a light sourceconsisting of either a bank of lights, referred to as a light bank, or afiber optic light source. Some of the first phototherapy light sourcesincluded light banks positioned over incubators or open bassinets, orunder hoods or transparent supports. Typically, the light sources usedin phototherapy consist of fluorescent tubes, metal halide lamps, orlight-emitting diodes (LEDs).

While light sources having light banks are still being used, suchdevices are not without their disadvantages. For instance, phototherapydevices using light banks require that patients wear eye protection thatis often uncomfortable. These devices also require that patients remainrelative stationary while receiving treatment. Furthermore, thesedevices are typically large and immobile, which thus, require patientsto visit the locations of the light sources each time a dosage isneeded. Light sources using light banks are disadvantageous for at leastthese reasons.

Fiber optic light sources were developed as a substitute forphototherapy devices containing light banks but have not eliminated allof the drawbacks associated with these devices. For instance, while thefiber optic lights are more mobile than light bank devices, the fiberoptic lights typically deliver lower overall amounts of light than thelight banks. Additionally, fiber optic lights are often used inconjunction with fiber optic mats having specific geometries. Oftentimes, the geometries of the fiber optic mats are compromised whenforces are placed on the fiber optic mats in order to place the fiberoptic mats in contact with patients' skin surfaces. This undesirablyresults in greater light intensity being concentrated near the lightsource than at other portions of the fiber optic mat.

LEDs are typically used as light sources for phototherapy. For instance,U.S. Pat. Nos. 6,290,713 and 6,096,066 describe flexible mats having aplurality of LEDs positioned in arrays that are coupled to a pluralityof conductive traces for emitting light. The LEDs are point sources thatdo not emit light over a broad area, but rather over a narrow area.Light produced by the LEDs is diffused and made more uniform by placingdiffusers in the mats near the LEDs. Without the diffusers, the arraysof LEDs are simply collections of point sources. Because diffusers areused, the LEDs cannot be placed in contact with a surface. Instead, thethickness of the diffuser limits the proximity with which the LEDs maybe positioned proximate to a surface. Thus, the amount of light that anLED emits is not the same amount of light that reaches the surfacebecause a portion of the light produced by the LED is lost when the LEDis not placed in contact with a surface.

LEDs produce a single wavelength of light. If more than one wavelengthof light is required, more than one type of LED must be used. In orderto operate the LEDs, the mats contain numerous conductors to providepower to each LED individually. These conductors significantly add tothe overall weight and complexity of the mats.

The mats are made even more complex with the addition of channels fordissipating heat. Use of the plurality of LEDs in such close proximityto each other produces high amounts of heat that can pose potentiallydangerous conditions. This heat is typically vented from the devicesusing channels between the LEDs. While the channels do allow a portionof the heat produced by the LEDs to be vented from the mat, not all ofthe heat generated is removed.

Thus, a need exists for a phototherapy device that delivers light in amore efficient manner while retaining the advantages of a flexible mat.

SUMMARY OF THE INVENTION

According to one aspect of this invention, the phototherapy bandage is aself-contained device that is formed from a base and at least one lightsource for emitting radiation and directing it toward a targetedlocation on a patient, which is defined to be a human or an animal. Inat least one embodiment, the phototherapy bandage is flexible andcapable of conforming to a patient, and more specifically, is capable ofbeing coupled to an exterior skin surface of a patient. In oneembodiment, the light source may be an electroluminescent (EL) device,which may be an organic or inorganic electroluminescent device.

The EL device may be capable of emitting radiation at differentwavelengths, such as all wavelengths forming visible light, includingred light, near-infrared radiation (NIR or near-IR), and mid-infraredradiation. The EL device is capable of providing illumination within alimited wavelength range to a target area from one to tens of squarecentimeters. The EL light source can be tailored to emit wavelengthsfrom visible light to near-infrared light by co-doping or by usingmultilayered EL structures. A single EL light source can be used totreat a range of conditions and can be fabricated to control flux anddose.

The EL light source may be coupled to the base using any connectionmechanism, and in one embodiment, the base may be coupled to at leastone light source using an adhesive. The adhesive may also be used tocouple the phototherapy bandage to a patient. The base may also includea moisture barrier for preventing moisture from contacting the lightsource.

The phototherapy bandage may also include one or more batteries, whichmay or may not be rechargeable, for powering the light source. Thephototherapy bandage may further have one or more microprocessors forcontrolling operation of the light source. The microprocessor mayoperate the light source continuously or intermittently depending on avariety of factors. The phototherapy bandage may further include amoisture barrier positioned on the light source to prevent the lightsource, the microprocessor, and the battery from contacting a fluid. Thephototherapy bandage may be used for aesthetic applications and forphotodynamic therapy.

An advantage of this invention is that the phototherapy bandage isflexible and capable of being attached to a patient to accelerate woundhealing and providing pain relief without interfering with the patient'sdaily activities.

Another advantage of this invention is that the light source is capableof being extended across the healing area of the bandage so that whenused the selected wavelength of light, which may be, visible light,near-IR light, or longer wavelength IR light, may be emitted in arelatively uniform manner towards the intended healing surface.

Another advantage of this invention is that the phototherapy bandage isa self-contained device that is easy to carry and wear.

Yet another advantage of this invention is that the phototherapy bandagemay be self-applied by the patient.

Another advantage of this invention is that the phototherapy bandage isportable and is relatively small, which enables the bandage to be packedin various hand bags, backpacks, hiking equipment, luggage and otherstorage devices.

Still another advantage of this invention is that the phototherapybandage may be contained in a moisture resistant package and applied toa patient when necessary.

Another advantage of this invention is that the phototherapy bandage maybe used for a relatively long duration when used with rechargeablebatteries.

Yet another advantage of this invention is that the EL source is capableof emitting both visible and NIR wavelengths.

Another advantage of this invention is that the EL source can emitmultiple NIR wavelengths at wavelengths that are known to havetherapeutic benefits in wound healing and pain relief.

Still another advantage of this invention is that the EL source may beformed from one or more layers or pixels that allow sequential orsimultaneous emission of light at different wavelengths.

Another advantage of this invention is that the EL source is capable ofoperating at or below freezing temperatures.

Yet another advantage of this invention is that the EL source may beoperated using low voltage.

Another advantage of this invention is that the EL source is capable ofemitting a uniform emission without use of diffusers.

Another advantage of this invention is that the EL source is rugged andcapable of absorbing the stresses commonly placed on a bandage.

These and other features and advantages of the present invention willbecome apparent after review of the following drawings and detaileddescription of the disclosed embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate preferred embodiments of the presentlydisclosed invention(s) and, together with the description, disclose theprinciples of the invention(s). These several illustrative figuresinclude the following:

FIG. 1 is an artistic rendering of an exemplary embodiment of aphototherapy bandage;

FIG. 2 is a schematic diagram of a side view of a phototherapy bandageof this invention;

FIG. 3 is a schematic diagram of the chemical structure of MEH-PPV;

FIG. 4 is a schematic diagram of the chemical structure for Ln(TPP)acac;

FIG. 5 shows an EL spectrum of MEH-PPV doped with 5 mol % Yb(TPP)acacmeasured at 9V and of MEH-PPV doped with 5 mol % Er(TPP)acac at 13V;

FIG. 6 is a cross-sectional view of a thin film electroluminescent lightsource;

FIG. 7 is a cross sectional view of another thin film electroluminescentlight source;

FIG. 8 is an exemplary pixel pattern for a first TFEL panel consistentwith certain embodiments of the present invention; and

FIG. 9 is an exemplary pixel pattern for a second TFEL panel consistentwith certain embodiments of the present invention.

DETAILED DESCRIPTION

The phototherapy bandage 10 of this invention is capable of providingradiation to a localized area of a patient, who may be a human oranimal, for accelerating wound healing and pain relief. In addition,phototherapy bandage 10 may also be used for photodynamic therapy andfor aesthetic applications. In one embodiment, phototherapy bandage 10is flexible and capable of being attached to a patient withoutinterfering with the patient's daily routine. Phototherapy bandage 10may easily conform to the curves of a patient and may come in a varietyof exterior shapes and sizes.

The term “phototherapy”, as used herein is intended to embrace bothphototherapy and photodynamic therapy. The term “infrared” as usedherein is intended to encompass the range of light spectrum aboveapproximately 650 nm and includes regions often termed “near-infrared”and includes “mid-infrared.” “Transparency” as used herein is defined aspassing a substantial portion of light at a wavelength of interest,while “reflectivity” is similarly defined as reflective of a substantialportion of light at a wavelength of interest. The term Thin FilmElectroluminescence (TFEL) as used herein should be interpreted to meanelectroluminescent (EL) devices that are made of stacked layers that aresubstantially planar in that the thickness of their essential lightcreation components is much smaller than their other dimensions. Thisterm is intended to embrace inorganic high field EL devices as well asorganic light emitting devices (OLEDs) (whether a dopant is used in theactive layer or not), which can be made with major dimensions rangingfrom millimeters to several inches and beyond. The term TFELspecifically excludes conventional inorganic semiconductor laser andconventional inorganic semiconductor diode devices such as LEDs and LDs(which may broadly fall within certain definitions of EL sources). Theterm TFEL also clearly specifically excludes incandescent lamps,fluorescent lamps and electric arcs. The term EL as used herein, isgenerally intended to mean TFEL. The term “dopant” as used herein canmean a dopant atom (generally a metal) as well as metal complexes andmetal-organic compounds used as an impurity within the active layer of aTFEL device. Some of the organic-based TFEL active layers may notcontain dopants. The term LED as used herein is intended to meanconventional inorganic (e.g., doped compound semiconductor based)semiconductor light emitting diodes. The term “OLED” is intended toexclude such conventional inorganic semiconductor LEDs, even though anOLED is often referred to as a type of organic based light emittingdiode.

In one embodiment, as shown in FIGS. 1 and 2, phototherapy bandage 10 iscomposed of one or more flexible light sources 12 that are coupled to abase 14. In at least one embodiment, a single light source 12 may beemployed. Phototherapy bandage 10 may further include an adhesive 16coupled to base 14 for attaching phototherapy bandage 10 to a patient.Phototherapy bandage 10 may also include a battery 18 and amicroprocessor 20 that may control light source 12. Battery 18 may becoupled to microprocessor 20 using any conventional devices, such as,but not limited to, one or more insulated electrically conductive wires.Battery 18 may be a conventional battery that is rechargeable or not andsized proportionally to be attached to base 14, as shown in FIG. 2.Battery 18 may be flexible and may have a thickness of about 0.5 mm with1.5 volts at 2.5 m Ah/cm². Multiple batteries may be used to achieve thedesired voltage. Microprocessor 20 may be programmable and capable ofcontrolling the operation of light source 12 in many ways.Microprocessor 20 may be integrated with a panel to select or set theoptical protocols, which will allow different doses, frequencies andtimes of exposure.

In one or more embodiments, light source 12 may be a light source thatis itself flexible and capable of emitting light in a substantiallysimilar intensity across the bandage 10. For instance, the light source12 may be, but is not limited to being, an electroluminescent device(EL) spread across a substantial portion of the base 14. The lightsource 12 may include only two electrodes that need to be connected to abattery 18, rather than the plurality of conductors used with arrays ofLEDs. This minimal number of conductors used in this invention reducesmanufacturing costs and complexity of the bandage 12 and enhances itsreliability. In one embodiment, the light source 12 may be a thin filmEL (TFEL) device. The EL light source 12 may be capable of emittinglight at both visible and NIR wavelengths. In addition, light source 12may be capable of emitting radiation substantially uniformly over atargeted area of a patient without the use of diffusers. The EL devicemay be configured to emit a single wavelength or multiple wavelengths oflight. The EL device may have one or more layers capable of beingactivated separately or together and have compositions that produce twoor more different emissions. The two or more layers may be turn onseparately or simultaneously.

The EL device forming light source 12 may be an inorganicelectroluminescent light source, as described in more detail below. Forinstance, the EL device may be formed from zinc sulfide doped with oneor more lanthanide elements, such as, but not limited to, neodymium,samarium, terbium, dysprosium, holmium, erbium, thulium, and ytterbium.The inorganic EL may include a thin layer of zinc sulfide doped with alanthanide sandwiched between two insulator films. The lanthanideconcentration may be between about 0.1% and about 2.0%, and the twoinsulator films may be made of silicon oxynitride. The inorganic EL mayinclude a reflecting electrode on a back surface of the device and atransparent electrode on the front surface of the device. The El deviceforming light source 12 may also be an organic light source such as, butnot limited to, the light sources described in more detail below.

Base 14 may be configured to be attached to a patient and conform to thecontours of the patient's outer skin surface or other surface. Inanother embodiment, base 14 is configured to be placed in closeproximity to a patient, but not in contact with the patient. Base 14 maybe any flexible material that is capable of conforming to the exteriorshape of human and animal bodies and may include, but is not limited to,biocompatible polymers or plastics. Base 14 also forms an illuminatingsurface from which radiation leaves phototherapy bandage 10.

Phototherapy bandage 10 may include one or more barriers 15 attached tothe top portion of base 14. Barrier 15 may prevent moisture fromcontacting battery 18 and microprocessor 20. In addition, barrier 15 maybe reflective so that light produced by light source 12 is reflected anddoes not pass through barrier 15.

Adhesive 16 may be coupled to one or more sides of base 14. Adhesive 16may be applied intermittingly or may be applied to cover an entire sideof base 14. In one embodiment, adhesive 16 is applied in strips to base14. Adhesive 16 may be any conventional adhesive and preferably hassufficient strength to keep phototherapy bandage 10 in contact with apatient while not having too much strength such that phototherapybandage 10 cannot be removed from the patient. As shown in FIG. 2,adhesive 16 may be located between base 14 and light source 12.

Phototherapy bandage 10 may include a barrier 22 coupled to light source12 for preventing moisture from contacting light source 12. Barrier 22may be photon transparent. Phototherapy bandage 10 may include wounddressing 24 coupled to a bottom surface of the bandage 10. Wounddressing 24 may also be photon transparent and sterile.

Phototherapy bandage 10 may be coupled to a patient by another person ormay be self-administered by the patient. In addition, phototherapybandage 10 may be stored in a moisture resistant package that may beeasily packaged together with a first aid kit or packaged separately foroutdoorsmen and others.

During use, phototherapy bandage 10 is coupled to a surface of apatient. The patient may attach phototherapy bandage 10 to himself orherself, or phototherapy bandage may be attached by someone else. Thephototherapy bandage 10 may be coupled to the wound site for any amountof time depending on whether the bandage is being used for pain reliefor tissue healing. In one embodiment, phototherapy bandage 10 isattached to a skin surface from three to ten days. While phototherapybandage 10 is attached to a patient, the bandage may emit lightcontinuously or intermittently, or both. The therapy process may becontrolled by microprocessor 20.

Electroluminescent Light Sources

The light source may be formed from electroluminescent materials capableof producing visible light, near-infrared (near-IR) radiation, andlonger wavelength radiation, such as mid-infrared radiation. In at leastone embodiment, the electroluminescent materials may be formed from aluminescent polymer and a metal containing compound where the metalcontaining compound incorporates a metal-ligand complex such that theabsorption spectrum of the metal-ligand complex at least partiallyoverlaps with the emission spectrum of the luminescent polymer. As theabsorption spectrum of the metal-ligand complex at least partiallyoverlaps with the emission spectrum of the luminescent polymer when theluminescent polymer becomes electronically excited, energy can betransferred from the luminescent polymer to the metal-ligand complex. Atleast a portion of the energy transferred from the luminescent polymerto the metal-ligand complex can then be emitted by the metal-ligandcomplex as near-infrared radiation. Conjugated polymers that areluminescent can be utilized.

In one embodiment, where the electroluminescent material may be aluminescent polymer and a metal-containing compound where themetal-containing compound incorporates a metal-ligand complex, theabsorption spectrum of the ligand of the metal-ligand complex at leastpartially overlaps with the emission spectrum of the luminescent polymersuch that when the luminescent polymer becomes electronically excited,energy is transferred from the luminescent polymer to the ligand. Energycan then be transferred from the ligand to the metal by sensitization.The energy transferred to the metal by sensitation may then be emittedas near-IR radiation or other radiation.

The energy transferred from the luminescent polymer to the metal-ligandcomplex or from the luminescent polymer to the ligand can be transferredby one or more mechanisms including, but not limited to, Förstertransfer and/or Dexter transfer. The luminescent polymer can becomeelectronically excited upon the creation of excitons in the luminescentpolymer by, for example, the application of an electric current throughthe luminescent polymer and/or exposing the luminescent polymer tophotons. Once created, the excitons within the luminescent polymer canbe mobile within the luminescent polymer. At least a portion of thesemobile excitons may then be trapped by the metal, or metal-ligandcomplex, within the luminescent polymer.

In another embodiment, the metal-containing compound can be a metalorganic compound. In at least one embodiment, the metal-containingcompound may include a lanthanide as the metal. The metal-containingcompound that includes a lanthanide may also include one or moreligands, which may be, but is not limited to being, a macrocyclicchelator, which is strongly light absorbing. The metal compounds thatmay be used are metals that include lanthanides such as, but not limitedto, Yb⁺³, Dy, Nd, Ho, Pr, Er⁺³, or Tm, sulfides, and halide compoundsand complexes such as oxy-compounds. The metal compounds may also beoxomolybdenum(IV) complexes, such as [MoOCL(CN-t-Bu)₄]⁺ and relatedcompounds, or Pt-Pd stacked complex such as [Pt(NC-R)₄ ²⁻] and relatedcompounds.

Ligands that may be utilized may include, but are not limited to, theentire family of light absorbing organic compounds that are known tobind to metal ions by chelation, coordinate covalent bonding, or otherbinding mechanisms. Specific examples include (1) tetraaryl porphyrins,wherein the aryl group may, or may not, be substituted with alkyl, alkylether, oligoether, alkyl sulfonate, alkyl amine, and/or othersubstituent groups or atoms, such as 5, 10, 15, 20-tetraphenylporphyrin,(2) octaalkyl porphyrins including octaethyl porphyrin, (3) chlorophyls,bacteriochlorophyls, chlorins, and other naturally and unnaturallyoccurring tetrapyrroler macrocycles, (4) texaphyins and relatedsubstituted and unsubstituted pentapyrrole macrocycles, (5)phthalocyanines, naphthophthalocyanines, and other structurally-relatedsubstituted and unsubstituted phthalocyanines.

Polymers that may be utilized may include, but are not limited to, theentire family of conjugated polymers including (1) those that are fullyconjugated, (2) those that include broken links of conjugation, and (3)those that incorporate copolymers of either block or random nature. Thepolymers and copolymers may have structures that include backbone, sidechains, graft, branch, hyperbranched, and/or dendritic. Examples ofconjugated polymers that may be used, include, but are not limited to:

-   -   1. Poly(arylenes) include polyphenylenes, polyfluorenes, and        polyanthracenes. Hydrocarbon aromatic polymers that have high        efficiency of light emission may also be used.    -   2. Poly(arylene vinylene)s including aromatic hydrocarbon        arylenes such as poly(phenylene vinylene), poly(anthracenylene        vinylene) and other aryl linked vinylene-based polymers.        Hydrocarbon vinylene-based polymers that have a high efficiency        of light emission may also be used. Poly(arylene vinylene)s        where the arylene unit is heterocyclic in nature, including        poly(thienylene vinylene) and/or poly(pyridine vinylene), known        for their red-shifted luminescence relative to PPV's and        oxadiazole-containing polymers, known for their enhanced        electron transport carrying capabilities.

3. Poly(heterocycle)s including poly(thiophene)s, known for theirenhanced hole transporting capabilities and poly(furans).

All of the polymer families can be functionalized to provideprocessability through solubility and fusibility. Substituent groupsinclude but are not limited to alkyl, alkyl ether, oligoether, alkylsulfonate, alkyl amine, and other groups.

Near-IR photoluminescence (PL) and/or electroluminescence (EL) can beachieved from blends of MEH-PPV with Yb(TPP)acac and/or Er(TPP)acac.FIG. 3 shows the structure for MEH-PPV and FIG. 4 shows the structurefor Ln(TPP)acac, where Ln=Yb³⁺, TPP=5, 10, 15, 20-tetraphenylporphyrin,and acac=acetylacetonate. These materials may involve sensitization of alanthanide-TPP complex by a conjugated polymer, which can lead to thenarrow bandwidth emission derived from, for example, Yb²F_(7/2)→²F_(7/2)(977 nm) and/or Er⁴I_(15/2)→I_(15/2) (1560 nm) transitions. A variety oflanthanides may be used to provide tunable PL and EL throughout thenear-IR region. For instance, Yb- and Er-TPP(acac) complexes can provideemission at 977 nm and 1560 nm, respectively.

The efficiency of the luminescence from lanthanides may be increased bycomplexing the ions with a ligand-chromophore that can serve to moreefficiently harvest the energy and sensitize the lanthanide's emission,for example, by exchanging energy transfer from the ligand-based tripletstate. The TPP ligand has a high degree of spectral overlap of itsQ-absorption bands with the MEH-PPV fluorescence allowing, for example,highly efficient Förster energy transfer. Due to the excellent spectraloverlap, addition of Yb(TPP)acac or Er(TPP)acac to MEH-PPV can lead toefficient quenching of the fluorescence from the conjugated polymerhost. Furthermore, in lanthanide porphyrin complexes, intersystemcrossing to the triplet state can occur with high efficiency, which mayapproach 100% in some embodiments. The ligand can also act as aneffective sensitizer to produce the spin-forbidden, luminescent F-statesof the lanthanide ions.

The electroluminescence material may be formed from a 100 nm thickspin-coated film produced by blending Yb(TPP)acac or Er(TPP)acac withMEH-PPV. FIG. 5 illustrates the photoluminescence of neat MEH-PPV (˜)and MEH-PPV doped with 2 mol % Yb(TPP)acac (−)based on polymer repeatunit), upon excitation at 350 nm. The spectrum of the blend is plottedon the same absolute scale as that of the neat polymer, with the y-scaleof the inset expended by a factor of 100. The MEH-PPV fluorescence thatappears at 589 nm is quenched approximately 98% when Yb(TPP)acac ispresent. Quenching of the visible emission may be accompanied by theappearance of the Yb emission at 977 nm in the near-IR. An excitationspectrum for the 977 nm emission shows a strong band that id due to thevisible absorption of the host polymer, demonstrating its role as asensitizer. Analogous results can be observed when Er(TPP)acac isblended into MEH-PPV, with the near-IR emission appearing at 1560 nm.

In at least one embodiment, the near-IR electroluminescent light sourcemay be formed from an indium-tin-oxide (ITO) glass coated with PEDOT/PSS(Bayer Baytrom P VP A1 4083) as a hole transport layer. TheMEH-PPV:Ln(TPP)acac blend may be spin coated from solution (1% wt of thepolymer in toluene) and the resulting film vacuum dried from 12 hours(1×10⁻⁶ torr) at room temperature. Calcium (50 Å) followed by A1 (1500Å) layers may then be thermally evaporated at 1×10⁻⁶ Torr withoutbreaking the vacuum between the metal depositions. After deposition, thelight source may be encapsulated with epoxy to minimize exposure tooxygen and moisture.

The light source 12 may also be a light source for phototherapy orphotodynamic therapy that can be positioned in close proximity to or indirect contact with the tissue or skin of the patient. In certainembodiments consistent with the present invention, the light source hasa thin, lightweight TFEL panel designed to provide uniform illuminationover the area to be treated without the use of diffusers that wouldattenuate a portion of the light output. A single illuminating unit canbe used as a TFEL panel requiring only two electrodes with twoelectrical connections, and can be made as large as several inches byseveral inches or even several feet by several feet. The light sourcemay be operated in a range of power and frequency that does not generateexcessive heat so that the light source surface may be used in contactwith a patient's skin without discomfort and without need for the use ofa cooling mechanism. The light source can be designed to emit light withwavelengths ranging from the visible to the infrared range. Selection ofthe appropriate wavelength allows the optimization of the light sourcefor specific treatments.

As shown in FIG. 6, an exemplary TFEL panel and associated circuitryconsistent with certain embodiments of the present invention isillustrated as 100. For purposes of the current discussion, start byassuming that this is an inorganic high field EL device. In this simpleembodiment, a thin film electroluminescent panel is fabricated bysandwiching an inorganic electroluminescent layer 104 between twotransparent insulators 108 and 112, which are further sandwiched betweena pair of electrodes 116 and 120. The seal material (glass or polymer)122 covers the light emitting portion of the device and protects theuser from the high voltage used to generate the light. In oneembodiment, the layer 122 also serves as a substrate for the growth ofthin films of the materials composing the TFEL panel. When layer 122serves only as a seal material, the substrate supporting the thin filmscan be placed beneath the bottom electrode 120. This produces a singleilluminating unit requiring only two electrodes that can be as large asseveral inches by several inches and even several feet by several feet.

In this exemplary embodiment, an active inorganic electroluminescentlayer 104 generates light by impact excitation of a light-emittingcenter (called the activator or dopant), embedded in a host material, byhigh-energy electrons. Since the electrons gain their energy from anelectric field (1-2 MV/cm), this type of EL is often called high fieldelectroluminescence (HFEL). A host matrix with an activator in thisembodiment can be in the form of inorganic thin film or powder dopedwith a metal ion (ions) or metal complex (complexes). In general, thehost material has a band gap large enough to emit light withoutabsorption as well as to provide a medium for the efficient transport ofhigh energy electrons. Examples of the inorganic host matrix forming theelectroluminescent layer include, but are not limited to, ZnS, SrS,ZnGa₂O₄, ZnSiO₄, CaSSe, CaS and others. Examples of active centersincorporated in the EL phosphor material include, but are not limitedto: Mn, Cu, rare earth elements (such as Ce, Nd, Sm, Eu, Tb, Tm, Er, Ndand others), and their complexes (TbOF and others). Theelectroluminescent layer 104 may be formed from ZnS, SrS, or an oxidelayer doped with the above-identified EL phosphor material.

To enhance the efficiency and shift the peak emission wavelength,co-doping can be also used (for example, Ag in SrS:Cu with Ag in SrS fora blue EL phosphor). The insulators 108 (for example, ATO, which is amixture of TiO₂ and Al₂O₃) and 112 (for example, barium tantalate, whichis BaTa₂O₄) on either side of the active layer limit the maximum currentto the capacitive charging and discharging displacement current level.The insulators 108, 122 may also be formed from silicon oxynitrideElectrodes sandwiching the insulator and EL layers form a basiccapacitive structure. Electrode 116 is a transparent conductiveelectrode such as, for example, an Indium Tin Oxide (ITO) electrode oraluminum, that permits light of a certain wavelength range to pass.Alternate electrode materials, such as nickel-cobalt spinel oxide, maybe used to extend the range of transparency further into the IR range.

Electrode 120 is preferably somewhat reflective (for example, Al) sothat light that is incident on electrode 120 will reflect back throughelectrode 116. In certain embodiments consistent with the presentinvention, the electrode closer to the area to be treated by the TFELlight source is transparent while the second electrode serves as areflector. Light emitted in the phosphor layer is uniform in alldirections. The reflecting electrode serves to reflect light generatedin the phosphor layer emitted in that direction as well as any lightreflected from the patient's skin not absorbed by the other layers inthe TFEL structure. Due to the reflective properties of the electrode,the overall light source efficiency is improved. The highest luminancereported in flat panel display industry for TFEL panel (pixelated) withinorganic emission layer in the visible region of light spectrumcurrently is >1000 cd/m² (>1 mW/cm²).

A typical thickness of the TFEL panel, not counting a substrate, isabout 1.5 mm. A typical thickness of a glass or polymer substrate in anEL device is about 1 mm. Thus the illuminating panel can be made to bevery light and compact. This structure can be extended in width toproduce a TFEL panel that is large in area and somewhat planar with avery thin cross section. Yet wiring to such a device may remain assimple as a two-wire connection.

In another embodiment, the active layer of the TFEL is an organic-basedmaterial. Organic-based electroluminescent light (OEL) sources have beenunder development for several years and may be particularly attractivefor PT applications because of their very simple fabrication techniques(for example, spin on coating of organic material), high brightnessemission in the visible and IR part of the spectrum and low operationalvoltage. The high brightness makes OEL displays attractive as a sourceof radiation and the low voltage operation allows the OEL sources to bebattery powered, which enhances their portability and ease of use in thefield.

FIG. 6 can also represent the structure of an OEL. In this case, theactive layer 104 is an organic material as will be described later. Theelectrodes 116 and 120 are similar or identical in structure to that ofthe inorganic HFEL source previously described. Instead of insulatinglayers 108 and 112, the OEL often uses an electron/(or hole)injection/(or blocking) layer that is similarly located. Additionally,the organic material forming the active layer may be made up of multiplelayers and may or may not have a dopant.

Currently, the typical luminance of OEL sources is between severalhundred cd/m² to several thousand cd/m². However, luminance as large asslightly less than 40000 cd/m² (corresponding to about 40 mW/cm²) in theregion of visible light has been observed. A large variety of polymers,copolymers and their derivatives have been demonstrated within last thedecade to posses EL properties. The configuration of such polymer-baseddevices may have a simple single layer, bilayers, or blends of polymersused to enhance efficiency, tune the emission wavelength or even providedevices that emit light of different colors simply by changing thedriving voltage. In the last case, as an example, a blend of twopolythiophene-based polymers can be cited, which posses two differentbandgaps and thus different emission colors and different turn-onvoltages. As described above, a typical single layer polymer organicTFEL is constructed by sandwiching a thin layer of luminescentconjugated polymer between an anode and cathode, where one electrode istransparent. Organic materials can be also be made up of emitting metalcontaining organic compounds (for example, aluminum,tris(8-hydroxyquinoline, and conjugated polymers)) incorporated into thepolymer host matrix also have been employed as OEL materials forgenerating visible light. When containing rare earth ions, emission frommetal containing organic compounds often exhibit sharp peaks in bothvisible and NIR spectral regions. Relatively recently, organolanthanidephosphors have been demonstrated to give high enough brightness andefficiency to underline their potential for use in OEL devices. OrganicTFEL devices are sometimes referred to as an OLED.

In one embodiment consistent with the present invention, organic-basedTFEL panel 100 has a layer 122 that forms a supporting substrate (glassor polymer) and that also serves as a sealing material protecting theorganic material from degradation, a transparent conducting electrode116 (such as, for example, ITO), a hole transport conducting polymerlayer 108 (such as, for example PEDOT-PSS), the active light emittinglayer 104, and the top electrode structure in the form of a calciumlayer 112 and aluminum layer 120, where Ca and Al can be substituted byother conductive materials with relatively low work function. Theemitting layer can be, for example, made of blends of MEH-PPV orPPP-OR11 with lanthanide-TPP complexes, where lanthanide can be Yb (peakemission at 977 nm), Er (1560 nm) and others.

In another embodiment, the OEL device emitting red light (612 nm peak)can have the following layers: glass (polymer)substrate/ITO/Eu(TTFA)3(phen):PBD:PVK/BCP/Ca/Al. In this embodiment, anew functional layer-BCP, is incorporated as a hole-blocking layersubstantially improving brightness and efficiency. In general, inaddition to the layers of materials described above, additional layersfor OEL device can be incorporated, such as electron or hole injectionor blocking layers. Other configurations are also possible withoutdeparting from the present invention.

In both inorganic and organic-based TFEL devices, a single emitting unitdriven by two electrodes can be substantially large due to much lowercurrent generated in these structures as compared to semiconductor LEDs.A single illuminating unit requires only two electrodes but can be aslarge as several inches by several inches and even several feet byseveral feet. The current within high field inorganic EL and OELs rangefrom several mA/cm² to about 100 mA/cm², while for semiconductor LEDs itis about 100 A/cm².

Light is generated in inorganic TFEL device 100 by application of an ACvoltage across electrodes 116 and 120 of sufficient magnitude to causeemission of light by the active layer 104. DC could be used but at theexpense of higher current drain. Electrical charge is injected into theactive layer, by application of voltage across the electrodes, excitingthe dopant atoms. Relaxation of the dopant atoms back to the groundstate results in the emission of photons characteristic of the dopantatom and the phosphor host. The wavelength of the light emitted isdetermined by the dopant or dopants in the active layer. Each dopantused in the TFEL panel will exhibit a unique spectral outputcharacteristic of that dopant. Often, if a single dopant is used, lightwill be emitted predominantly at a single wavelength, but often a singledopant will also result in multiple dominant lines in the outputfrequency spectrum. Multiple dopants, such as, but not limited to three,can be effectively used to generate light at multiple wavelengths orspectra.

Inorganic TFEL devices have been optimized for emission in the visiblewavelength range specifically for display applications using, forexample dopants such as copper to produce blue emission and manganese toproduce amber emission. Doping the phosphor layer with a rare-earthelement, a strong EL emission band produces light in the infrared rangeaccompanied in many cases by some level of emission in the visiblerange. The selection of the appropriate dopant allows the characteristicEL emission to be changed to wavelengths ranging from the visible to theinfrared. The spectrum can also be modified somewhat by annealing. Theemission is determined by the specific dopant used. The use of two ormore dopants can produce multiple characteristic emission lines. Thewavelengths may be chosen to match the portions of the electromagneticspectrum known to have therapeutic benefit in phototherapy, or toactivate the photoreactive agent in photodynamic therapy. Someillustrative dominant wavelengths associated with several dopants aregiven by Table 1 below. This listing should not be considered exhaustiveor limiting, but merely illustrative of the ability to produce ELemissions in the range of wavelengths that are useful for phototherapyapplications. TABLE 1 INORGANIC AND DOMINANT LIGHT ORGANIC EL MATERIALWAVELENGTHS EMITTED (MATRIX:DOPANT) FROM EL SOURCE ZnS:Tm (Thulium) 480nm and 800 nm ZnS:Nd (Neodymium) 890 nm ZnS:Er (Erbium) 550, 660 and 980nm ZnS:Mn 580 nm (yellow) SrS:Cu 475 nm (green/blue) (SrS:Cu, Ag) (430nm) (blue) SrS:Ce 510-550 nm double peaked Eu(TTFA)₃(phen):PBD:PVK 612nm (red) Yb(TPP)acac:MEH-PPV 977 nm

Light emitted from a TFEL source such as described herein is generallynot a pure light at any given wavelength. Rather, the light sourceproduces a spectrum of light that frequently exhibits sharp peaks inintensity at one or more wavelengths. The approximate wavelength of thedominant intensity peaks are listed in the table above for the exemplarydopants listed. Uniform light intensity over the entire light sourcesurface area is achieved with uniform dopant distribution and filmthicknesses in the TFEL panel, parameters readily controlled during themanufacturing process.

In the phototherapy device 100 of FIG. 6, a variable voltage source 126supplies AC voltage to the TFEL panel electrodes 116 and 120 to induceemission of light. In this embodiment, the variable voltage sourcesupplies a voltage under control of microprocessor 130. Themicrocontroller may control any one or more desired parameters of the ACvoltage including, but not limited to, voltage level, frequency andmodulation characteristics to control the light output from the TFELpanel. The desired output level and other parameters can be controlledby user input to a control panel 134 operating as a user interfaceproviding I/O functions to the microprocessor 130. Such parameters maybe directly controlled in some embodiments or controlled as a functionof treatment selections made at the control panel without knowledge ofthe actual physical parameters being influenced.

In the embodiment illustrated, if multiple dopants are used anduniformly distributed, then light is emitted at multiple frequencies ata variable intensity level and time that is controllable bymicroprocessor 130 which acts as a controller upon appropriate receiptof user input at control panel 134. According to this design, the TFELsource can be manufactured and operated as a single light source withthe entire panel uniformly activated. One or more conductive elements isattached to both the top and bottom electrode of the TFEL panel andconnected to a suitable power source such as source 126. This simpledesign results in a reliable TFEL light source since there are minimalcomponents and minimal connections, and produces a device that is lightin weight with low heat generation and low current drain. In thisembodiment, all available spectra of light from the TFEL panel areproduced whenever an appropriate voltage is applied to the panel. Forinorganic TFEL, a relatively high voltage (about 200V) may be requiredto produce light emissions. In this case, the voltage source 126 mayincorporate a voltage converter to appropriately boost the voltage torequired levels. However, it should be noted that high voltage does notimply limitations on portability. In addition, TFEL displays have superbshock resistance and can normally operate at −25° C. to +65° C.

In an alternative embodiment, as illustrated in FIG. 7, a phototherapydevice 200 is illustrated in which multiple light spectra areindividually selectable. In this embodiment, two or more TFEL panels arestacked to provide the user with the ability to individually addresseach panel and thus select one of two wavelengths, or sets ofwavelengths, for the phototherapy treatment protocol. For an inorganicTFEL, the first panel structure is similar to that of FIG. 6 in whichthe active layer 104, surrounded by insulators 108 and 112 arepositioned between transparent electrode 116 and electrode 120(Electrode 120 is preferably reflective at the wavelengths ofinterest.). A second TFEL panel is fabricated by positioning a secondactive layer 204 between two transparent insulators 208 and 212. The twotransparent insulators 208 and 212 are in turn positioned between a pairof transparent electrodes 216 and 220. Electrode 220 is then coupled toelectrode 116 using a transparent insulating glue or tape 224 or othermechanism to hold the two panels together. In another embodiment, asingle electrode may be substituted for electrodes 220 and 116 byappropriate modification of the outputs from the variable voltagesource. In an organic TFEL embodiment, the structural changes discussedin connection with FIG. 6 can be applied equally to the structure ofFIG. 7 to achieve a multiple layer organic active layer TFEL.

In this embodiment, variable voltage source 226 supplies voltage acrosselectrodes 116 and 120 and across electrodes 216 and 220. The device isagain isolated from the user's skin by a seal layer 122. Thus, the lightemission from the top panel and the bottom panel can be independentlyselected by selective application of voltage to the two stacked TFELpanels. Due to having to pass through the upper TFEL panel, emissionsfrom the lower TFEL panel will be slightly attenuated compared to thosefrom the upper TFEL panel, and this should be accounted for indevelopment of treatment protocols. Since the thickness of each EL panelcan be about 1 mm, the attenuation is generally low (about 10%). Theoutput, as in device 100, is selected by controlling the variablevoltage source 226 by microprocessor 230, operating under control of acomputer program with the user input selected via control panel 234. Dueto the low current consumption of the TFEL panel, this apparatus (aswell as apparatus 100) may be readily battery powered by battery 240.Battery 240 can either be replaceable batteries or may be a rechargeablebattery that can be charged by battery charging circuit 244. Thiscircuit may also incorporate voltage regulators and voltage converters(for inorganic TFEL) and other peripheral circuitry as will be clear tothose skilled in the art to assure uniformity of voltage, etc.

An alternate embodiment involves producing a patterned array of TFELpixels in order to produce multiple characteristic emission lines. Someof the pixels are designed to emit one wavelength or spectrum whileothers are designed to produce an alternate wavelength or spectrum bydoping the phosphor used to generate the two types of pixels withdifferent dopants. the pixels can be interconnected so that all thepixels of one type can be activated simultaneously. The two, or more,pixel types could be switched on separately to generate emissioncharacteristic of the activated pixels or rapidly switched on and offsequentially producing both types of emission.

FIG. 8 illustrates one embodiment that uses arrays of pixels in aprescribed pattern to produce multiple spectra of light emissions. Inthis embodiment, a checkerboard pattern is used with alternatingsegments of doped electroluminescent material being doped with twodifferent dopants. For example, a first dopant can be used to dopesegments 702 (represented by the white squares), while a second dopantcan be used to dope segments 706 (represented by the hashed squares) inthe same manner used to create pixels in a video display. In a case oforganic TFEL based on light emitting polymers which do not requiredopants, these segments can be made of different types of light emittingpolymers. Electrodes are fabricated so that each of the segments 702 canbe collectively addressed (again in a manner similar to that used invideo displays, except that all pixels associated with each spectrum canbe addressed simultaneously) and each of the segments 706 can becollectively addressed. The user can then address segments 702 withappropriate drive voltage to produce light at the wavelength associatedwith the dopant used in the segments associated with 702. The user canseparately or simultaneously address the segments 706 associated withthe second dopant to produce light having different spectralcharacteristics. As the segments are made small and smaller, the lightfrom the panel becomes more uniform, but the panel becomes somewhat morecomplex and expensive to manufacture. Similarly, depending onapplications, a TFEL panel with only one dopant can also be pixilated.The pixel size can range from several mm to several inches.

A somewhat simpler structure is illustrated in FIG. 9 in whichalternating segments of the panel with first and second dopants arefabricated in successive columns. Thus, a column 802 has the firstdopant and the column 806 has the second dopant. Again, the complexityof manufacture increases as the columns are made smaller, but theuniformity of the output becomes better. Of course, those skilled in theart will appreciate that other arrangements of doped segments of thepanel can be devised, and that the present invention is not limited totwo such dopants. Moreover, multiple dopants can be used for each of thesegments of the panel and multiple layers can be used with theseembodiments without departing from the present invention.

In addition to the embodiments described in connection with FIGS. 8 AND9, multiple layers (similar to the embodiment shown in FIG. 7) can beused to generate the pixels with an upper layer contributing to a firstspectrum and the lower layer contributing to the second layer with thepixels alternating with one another as in FIGS. 8 and 9 to provide theuser with the option of selection of either of the two spectra.

As previously noted, a further aspect of the present invention is theability to bring the light source 12, the TFEL panel, in direct contactwith the skin without the necessity of a cooling device. Other lightsources, such as LEDs, exhibit higher power dissipation than TFELdevices. LEDs often produce a significant amount of heat and may requirea cooling mechanism. The TFEL light source 12 may feel warm when incontact with the skin under normal operating conditions, but does notproduce enough heat to require supplemental cooling. The TFEL lightsource 12 can be comfortably and safely used for extended periods oftime.

The foregoing is provided for purposes of illustrating, explaining, anddescribing embodiments of this invention. Modifications and adaptationsto these embodiments will be apparent to those skilled in the art andmay be made without departing from the scope or spirit of thisinvention.

1. A phototherapeutic bandage, comprising: a base formed from a flexiblesubstrate; a thin film flexible electroluminescent source coupled to thebase and extending continuously across at least a portion of the basefor emitting radiation to a target area on a patient; and wherein thebandage is capable of conforming to a surface area of the target area.2. The phototherapeutic bandage of claim 1, further comprising anadhesive layer having a first and second side, wherein the first side ofthe adhesive layer is attached to the base and the second side is forfastening said bandage to a target area on a patient.
 3. Thephototherapeutic bandage of claim 1, wherein said electroluminescentsource is a single continuous film having an area which substantiallycovers the base and said continuous film area is adapted to emitsubstantially uniform radiation across the base.
 4. The phototherapeuticbandage of claim 1, further comprising an optically transparent moisturebarrier layer over the electroluminescent source.
 5. Thephototherapeutic bandage of claim 1, wherein said electroluminescentsource is an inorganic electroluminescent source and comprises anelectroluminescent layer positioned between two transparent insulators,wherein the two transparent insulators are positioned between twoelectrodes.
 6. The phototherapeutic bandage of claim 5, wherein the twotransparent insulators are selected from the group consisting of ZnS,SrS, ZnGa₂O₄, ZnSiO₄, CaSSe, CaS, and silicon oxynitride.
 7. Thephototherapeutic bandage of claim 5, wherein the two transparentinsulators are selected from the group consisting of ATO and bariumtantalate.
 8. The phototherapeutic bandage of claim 5, wherein theelectroluminescent layer is selected from the group consisting of Mn,Cu, Ce, Nd, Sm, Eu, Tb, Tm, Er, and Nd and as sulfides, halide compoundsand complexes such as oxy-compounds.
 9. The phototherapeutic bandage ofclaim 5, wherein the electroluminescent layer is selected from the groupconsisting of Ag in SrS, and Cu with Ag in SrS for a blue EL phosphor.10. The phototherapeutic bandage of claim 5, wherein the two electrodesare selected from the group consisting of aluminum, indium tin oxide andnickel-cobalt spinel oxide.
 11. The phototherapeutic bandage of claim 5,wherein the electroluminescent layer is pixilated and capable ofproducing radiation in a plurality of narrowband wavelengths.
 12. Thephototherapeutic bandage of claim 5, wherein said inorganicelectroluminescent source comprises zinc sulfide doped with at least onelanthanide.
 13. The phototherapeutic bandage of claim 1, wherein saidelectroluminescent source is an organic electroluminescent source andcomprises an electroluminescent layer positioned between two electroninjection layers, wherein the two electron injection layers arepositioned between two electrodes.
 14. The phototherapeutic bandage ofclaim 1, wherein said electroluminescent source is formed from aluminescent polymer and a metal containing compound, wherein the metalcontaining compound comprises a metal-ligand complex, wherein theadsorption spectrum of the metal-ligand complex at least partiallyoverlaps with the emission spectrum of the luminescent polymer such thatwhen the luminescent polymer becomes electronically excited, energy istransformed from the luminescent polymer to the metal-ligand complex,wherein at least a portion of the energy transferred from theluminescent polymer to the metal-ligand complex is emitted by themetal-ligand complex as near-infrared radiation.
 15. A phototherapeuticbandage, comprising: a base formed from a flexible substrate; anadhesive layer having a first and second side, wherein the first side ofthe adhesive layer is attached to the base and the second side is forfastening said bandage to a target area on a patient; a single,continuous, thin film, flexible electroluminescent source coupled to thebase and extending continuously across at least a portion of the basefor emitting radiation to the target area on a patient; wherein thebandage is capable of conforming to a surface area of a body to betreated; and wherein the electroluminescent source is capable ofproducing near-infrared light.
 16. The phototherapeutic bandage of claim15, further comprising an optically transparent moisture barrier layerover the electroluminescent source.
 17. The phototherapeutic bandage ofclaim 15, wherein said electroluminescent source is an inorganicelectroluminescent source and comprises an electroluminescent layerpositioned between two transparent insulators, wherein the twotransparent insulators are positioned between two electrodes.
 18. Thephototherapeutic bandage of claim 17, wherein the electroluminescentlayer is selected from the group consisting of ZnS, SrS, ZnGa₂O₄,ZnSiO₄, CaSSe, and CaS.
 19. The phototherapeutic bandage of claim 15,wherein said electroluminescent source is an organic electroluminescentsource and comprises an electroluminescent layer positioned between twoelectron injection layers, wherein the two electron injection layers arepositioned between two electrodes.
 20. The phototherapeutic bandage ofclaim 15, wherein said electroluminescent source is formed from aluminescent polymer and a metal containing compound, wherein the metalcontaining compound comprises a metal-ligand complex, wherein theadsorption spectrum of the metal-ligand complex at least partiallyoverlaps with the emission spectrum of the luminescent polymer such thatwhen the luminescent polymer becomes electronically excited, energy istransformed from the luminescent polymer to the metal-ligand complex,wherein at least a portion of the energy transferred from theluminescent polymer to the metal-ligand complex is emitted by themetal-ligand complex as near-infrared radiation.